Floyd took away a whole dune at the south end of the island, she said.

"We lost two miles of dunes in those storms in 1999," said J.B. Miller, biologist for the state park system including Anastasia State Park at the north end of the island.

Such is the life of a barrier island.

"Barrier islands are dynamic. They're always moving," Chandler said. "There's no way to nail down a beach."

While sand was building up under some residential docks on the south side of Matanzas Inlet following the 1999 storms, the opposite was happening at the county pier.

In fact, the north end of the island missed out on a lot of sand.

Roughly 200,000 to 250,000 cubic yards of sand travel past St. Augustine Beach each year. And it's not stopping to visit.

"The inlet blocks a substantial amount of that," Miller said. "It takes a lot of that sand."

St. Johns County relies on the dredged St. Augustine Inlet for navigation. In addition to recreational boating, the Army Corps of Engineers reported commercial traffic of less than 1 million pounds of nonelectric machinery traveling through the inlet in 2002.

The dredged inlet also contributes to erosion of the beaches at the north end.

"It's pretty clear to us it's eroded at a pretty rapid pace," said Paul Crawford, park manager at Anastasia State Park.

click photo to enlarge

Eroded sand from Anastasia Island travels south settles to form a sandbar around the Matanza Inlet and makes a convenient resting place for sea birds.

By PETER WILLOTT, Staff

The area around the pier is one of the most critically eroded beaches in the state, Miller said. And in 2000, the ocean was fast approaching A1A Beach Boulevard."The erosion was going to threaten the highway," Crawford said.

In response, a beach renourishment project in 2001 and 2002 added 4 million cubic yards of sand to the north end of Anastasia Island at a cost of $19 million -- $17 million in federal funds for the beach and $2 million in state money to build berms and dunes."The federal project did not have any dune building," Miller said.

However, sand continues eroding rapidly near the pier, Crawford said. So the state established a maintenance plan.

Miller said the state has mandated an erosion control line. When the beach has eroded to that point -- probably in three to five years -- the Corps of Engineers will begin planning another renourishment as part of a 50-year project.

"That's not to say Congress will authorize any spending," Miller said.

Meanwhile, the sand is heading south and depositing around Matanzas Inlet.

"The beach is building up again," Chandler said. "That sand is being washed out from Anastasia."

Sand from the north end is also building up the sandbar at the entrance to Matanzas Inlet, where herons, pelicans and seagulls frequently rest at low tide.

But the sand is not replacing the dunes there because visitors continue to drive on the flattened surface where the dune had been.

The tidal flow also moves sand and sandbars around. The flow comes from extensive marshlands drain into Pellicer and Moses creeks.

"All that water has to go through that inlet," Chandler said. "All the time that inlet is changing."

Within 12 hours of a tide coming in and out, a beach's profile can change, said Dave Williams, county aquatics superintendent.

"You can sometimes watch it change from tide to tide," he said.

The changes not only affect topography.

"It affects a lot of things," Williams said. "Both inlets are trying to fill in It's pretty dangerous from time to time."

Williams said rip currents seem more frequent, more severe and more long lasting.

"The transport is much faster," he said. "That concerns us."

Tidal flow not only affects sandbars, but also affects visibility. For example, in South Florida, a lifeguard can look underwater and see 35 feet. But here, visibility may be limited to 1 foot.

In response to the changing conditions, Williams said lifeguards have stepped up patrols and trained for specific events that occur with those conditions. For example, lifeguards spent two sessions a week last winter training in treacherous currents.

"We've got a good understanding of where are the major problem areas," he said.

Two such areas include the 21/2 mile stretch around the county pier and Vilano Beach, where rocks that had been covered for six or seven years have emerged.

Matanzas Inlet offers a different challenge.

The water around the south end of Anastasia Island may be shallow, but the currents move fast. Parents and children may feel safe wading in inshore ponds, but when the tide changes, the water can be moving at 6 to 10 knots, Williams said.